To view other calendars in Outlook on the web, click the Calendar icon, select Add calendar in the left navigation pane, and choose From directory to search for colleagues, or accept a sharing invitation. Once added, check the box next to the calendar name under "People's calendars" or "Other calendars" to view it.
Steps to View Shared Calendars in Outlook Web:
+ Go to the Calendar module and click "Add Calendar".
+ Select From directory and enter the name or email address of the person.
+ Click Add.